The use of optical sensing systems in industrial and other environments has grown substantially in recent years. Such systems include a source of light (preferably a source of modulated light) and a photodetector. Both the source and the detector may be mounted in a common housing, or they may be mounted in separate housings. When the source and the detector are mounted in a common housing, a suitable reflector (such as a corner reflector) positioned some distance from the source/detector housing reflects light from the source back to the photodetector. When the source and the detector are mounted in different housings, the source light usually impinges directly on the photodetector without being redirected. In either structural arrangement, a change in the detection of the light beam creates control signal information that is utilized to control various types of equipment. The change may be the interruption of the light beam by a passing object or the change may be the detection of the light beam normally interrupted by the presence of an object. For example, in optical sensing system can be used to detect the presence of objects on a conveyor moving past a particular point. Each time the beam is interrupted by an object, the detector produces a pulse, which is counted. Other examples are the use of optical sensing systems to sense the presence or absence of a web, or whether a container is filled to a suitable level. As will be readily appreciated by those skilled in the optical sensing art, these are only a very few examples of the many industrial uses to which optical sensing systems are put.
As will be understood from the foregoing description, one of the requirements of optical sensing systems is that the light source and the photodetector be aligned. In the case of separately housed light sources and photodetectors, the source housing and the associated detector housing must be aligned (with or without reflection) such that the light beam impinges on the light sensitive surface of the photodetector. In the case of commonly housed sources and detectors, the source/detector housing must be aligned with a corner reflector so that the source beam is reflected back to the light sensitive surface of the photodetector. The present invention is directed to a mounting device suitable for use with either arrangement.
In the past, mounting devices for the source and/or detector housings of optical sensing systems have ranged from simple clip mounts, through swivel mounts, to ball swivel mounts. All of these mounts have undesirable features. The range of alignment provided by clip mounts is very limited. While swivel mounts have more flexibility than clip mounts, their range of adjustment is also severely limited.
The main disadvantage of prior art ball swivel mounts has been their inability to be integrally formed with optical system source and/or detector housings, plus the fact that they have been undesirably expensive. In this regard, in the past, ball swivel mounts utilized in optical sensing systems have comprised a two-piece sheet metal bracket surrounding a ball. The pieces of the sheet metal bracket include aligned holes that allow the bracket to be attached to a suitable support surface and one of the two pieces includes a hole through which a locking bolt projects. While providing a substantially larger range of adjustment than clip and swivel mounts, ball swivel mounts of the type just described are unsuitable for integral formation with optical system source and/or detector housings. Further, such mounts are undesirably expensive. As a result, there is a need for a mount for optical system source and/or detector housings having the adjustment range of a ball and swivel mount that is substantially less expensive, and suitable for being integrally formed with such housings.
In order to reduce the time required to design optical sensing systems and provide for compatability between system components, certain industry standards have been set. Among these standards is the spacing between the mounting holes of brackets used to support the light source and/or detector housings of optical sensing systems. The industry standard has been set at thirty (30) millimeters. Another standard is the use of conduit to protectively house wires running to and from the light source and/or detector housings of optical sensing systems. The most common conduit size is one-half (1/2) inch. As a result, there is a need for a mount for optical system light source and/or detector housings that meets industry standards as well as the reduced cost and integral features described above.